AUSTIN, Texas (AP) ― Members of the ascendant rock band Alabama Shakes can tell you all about buzz in the 21st century.

They first read about themselves on the Internet about nine months ago. They began playing in packed houses for enthusiastic fans after putting out a hastily released EP just six months ago. And this week the foursome will reach the pinnacle of their exposure ― so far ― with a jam-packed schedule over five days at the South By Southwest Music Conference and Festival.

With thousands of reporters, bloggers, fans and members of the music industry jostling to see them and with the immediate “thumbs up, thumbs down’’ nature of the Internet culture, they’ll be judged and judged often, and they haven’t even released their first official album yet (that comes next month).

Still, drummer Steve Johnson thinks the band is ready for their moment in the spotlight.

“I think we play well under pressure,’’ Johnson said. “Sometimes, if we feel a little pressure, the heat is on, and sometimes it pushes us to play in ways we haven’t before, maybe a little bit tighter or something. So I don’t mind that pressure.’’

Justin Gage, a blogger for the music website Aquarium Drunkard, which is hosting a showcase this year featuring the band, says the Shakes are the sort of band the conference has touted since its start.

“South By Southwest is kind of the ultimate public showcase/coming-out party for a band, especially a band like Alabama Shakes, which has had so much attention over the last six months,’’ said Gage, a 15-year attendee. “Anyone that has anything to do with the music industry as it is, they’re pretty much going to be at South By Southwest. It’s a prime opportunity for a band like them that are already superbuzzed about. This is a great time for all these people who have been hearing about the buzz for the past year to see it in the flesh.’’

They’re not the only act tagged with the “one to watch’’ label. Austin bluesman Gary Clark Jr., British soul singer Michael Kiwanuka, Brooklyn punk rockers The Men and Philadelphia psych rockers The War on Drugs are all generating attention.

But even buzzworthy acts are having a harder time standing out with more and more chart-toppers and musical icons descending on what used to be primarily a venue for emerging acts.

This year, SXSW may have landed their biggest name yet with Bruce Springsteen serving as the conference’s keynote speaker and performing to promote his latest album, “Wrecking Ball,’’ released earlier this month. Jay-Z kicked off the week with a hit-filled, 80-minute performance Monday night (though the music portion of the SXSW Festival, which also includes film and interactive, actually starts Tuesday).

The Boss and Hova represent just the tip of the VIP list. Lil Wayne, 50 Cent, Nas, T.I., B.o.B. and several other hip-hop acts are coming and there are persistent rumors that Eminem will appear. Multiplatinum Grammy winner Norah Jones is also performing, as are Jack White, Fiona Apple and critically acclaimed singer-songwriter Santigold, who will debut new songs.

That means these days new bands need buzz even before they arrive.

“I think anything is possible, I’ll say that,’’ Gage said. “But I do agree that in 2012 unless you have kind of all the different pieces in place for initial buzz, I do think it’s much more difficult to be that breakout band unless you’ve had those kind of collective rumbling before arriving in town.’’

Clark, another rising performer, is in Stage 2 of that process. He grew up in Austin and played sporadically at the festival over the years. But he stepped it up last year, playing nine times before heading to Bonnaroo and releasing an EP. He parlayed those successes into an opening spot for Eric Clapton in front of 70,000 fans in Brazil and playing for President Barack Obama, a run he says is “dreamlike, actually, and kind of surreal.’’

This year he’s even more visible at South By Southwest with eight shows, including a performance slot on MTV’s Woodie Awards, as he prepares to release his major label debut in September. The ride has been interesting and the buzz palpable.

“I’ve definitely felt it over the years,’’ Clark said. “It’s pretty cool.’’